// Copyright 2016 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef V8_BASE_RING_BUFFER_H_
#define V8_BASE_RING_BUFFER_H_

#include "src/base/macros.h"

namespace v8 {
namespace base {

    template <typename T>
    class RingBuffer {
    public:
        RingBuffer() { Reset(); }
        static const int kSize = 10;
        void Push(const T& value)
        {
            if (count_ == kSize) {
                elements_[start_++] = value;
                if (start_ == kSize)
                    start_ = 0;
            } else {
                DCHECK_EQ(start_, 0);
                elements_[count_++] = value;
            }
        }

        int Count() const { return count_; }

        template <typename Callback>
        T Sum(Callback callback, const T& initial) const
        {
            int j = start_ + count_ - 1;
            if (j >= kSize)
                j -= kSize;
            T result = initial;
            for (int i = 0; i < count_; i++) {
                result = callback(result, elements_[j]);
                if (--j == -1)
                    j += kSize;
            }
            return result;
        }

        void Reset() { start_ = count_ = 0; }

    private:
        T elements_[kSize];
        int start_;
        int count_;
        DISALLOW_COPY_AND_ASSIGN(RingBuffer);
    };

} // namespace base
} // namespace v8

#endif // V8_BASE_RING_BUFFER_H_
